Radar wind profilers and other instruments were deployed in coastal New Hampshire and surrounding areas for the New England Air Quality Study in summer 2002. We report observations of the coastal boundary layer structure with emphasis on pollutant transport. Air pollution episodes in northern New England often are caused by transport of pollutants over water and involve two crossings of the coast. In some cases, the pollutants that affected coastal New Hampshire and Maine were transported over coastal waters in shallow stable layers at the surface. These layers were at least intermittently turbulent but retained their chemical constituents. In one case, the sea breeze played an important role in pollutant transport. It is likely that overwater transport in elevated layers is also important for some episodes and for long-range transport, but elevated transport did not play a major role in summer 2002.